1. Field of the Invention:
This invention relates to a soft capsular preparation comprising sodium picosulfate, and more particularly, to a soft capsular preparation comprising a polyethylene glycol solution of sodium picosulfate. The soft capsular preparation is stable over a prolonged storage time and is convenient to carry around. In addition, an exact dosage of the medicine can be administered.
2. Description of the Background
Sodium picosulfate [4,4,-(2-pyridilmethylene)diphenolbis(sodiumsulfate)monohydrate]is widely used as a medicine for constipation (laxative).
A sodium picosulfate preparation is commercially available in a syrupy liquid form. Conventionally, it is administered by dissolving in water when used.
Such a liquid form preparation is, however, inconvenient to carry around. In addition, the dosage must be measured every time it is administered.
There is, therefore, a need for sodium picosulfate in a solid preparation form. However, long-term storage in a solid form results in deterioration with browning or decomposition. The solid form preparation is thus accompanied by drawbacks.
In order to improve the long-term storage stability of sodium picosulfate, preparation in a soft capsular form might be suggested. Unfortunately, however, this technique is not good because sodium picosulfate, white crystal powder, is sparingly soluble in oily substances, although it is readily soluble in water.
A sot capsular preparation was developed as the most suitable preparation form capable of containing oily substances. Recently, there has been a strong desire to formulate water-soluble substances as well in soft capsular form. Various studies in this respect have been undertaken.
Conventionally known methods for incorporating water-soluble substances in a soft capsule can be roughly divided into the following three methods:
(1) A method of preparing a W/0 emulsion from a water-soluble substance and an oily substance using a surface active agent. The W/0 emulsion is encapsulated into a soft capsular film to prepare a soft capsular preparation. PA0 (2) A method of preparing a suspension of an oily substance in a mixture of water-soluble substance and bees wax. The suspension is encapsulated into a soft capsular film, and changed to a semi-solid state by using thixotropy to prepare a soft capsular form. PA0 (3) A method of having a water-soluble substance adsorbed on an adsorbent, such as a light silicate anhydride and the like, and preparing a suspension of such a light silicate anhydride in an oily solution. The suspension is encapsulated into a soft capsular film to prepare soft capsular form. PA0 (a) All of the above three methods necessitate a large volume of contents to be encapsulated. This makes the capsule bigger and the administration difficult. PA0 (b) All of the above three methods require to encapsul suspensions which are opaque. In order to improve the outward appearance of the product for promoting commercial value of the product, unnecessary substances, including pigment, titanium oxide, or the like should be formulated in the capsular film. PA0 (c) When the soft capsular agent prepared by method (1) is left under severe conditions for an extended period of time, e.g. exposed to high temperature conditions, the emulsion becomes unbalanced and the contents tend to ooze out through the capsular film. PA0 (d) The surface film of the soft capsule prepared by method PA0 (2) gradually looses the solubility due to the influence of bees wax, resulting in a delayed degradation time. PA0 (e) In method (3), the adsorbent used has a light density and is bulky, thus requiring an increase number of manufacturing processes and a high production cost.
All of these conventional methods, however, have the following drawbacks.
In view of this situation, the present inventors have undertaken extensive studies, and found that a soft capsular preparation of sodium picosulfate which is stable for an extended period of time can be prepared by dissolving sodium picosulfate in polyethylene glycol and encapsulating the solution into a soft capsular film. This finding has led to the completion of the present invention.